Differential effects of lorazepam and oxazepam on priming.

The effects of lorazepam (2 mg), oxazepam (30 mg) and placebo on performance in implicit and explicit memory tasks were compared in a double-blind, independent group study with 36 healthy volunteers. Both benzodiazepines (BZs) impaired performance on the explicit task (free recall). However, only lorazepam impaired performance of the implicit task (word-stem completion). A similar pattern of drug effects was observed on a secondary task which used different instructions at stimulus presentation. BZ effects on the explicit task were more associated with levels of sedation (indexed by finger tapping speed) than their effects on the implicit task. It is concluded that both BZs impair episodic memory but only lorazepam impairs priming.